This is a proposal to continue work already underway on the prevention of the intracranial arterial necrosis associated with subarachnoid hemorrhage. Previous work has demonstrated that this vasculopathy can be markedly reduced by the injection of the thromboletic agent Plasmin directly into the cisterna magna. This proposal is to further characterize the proper timing to insure maximal protection and to determine if prevention of the vasculopathy will also prevent delayed vasospasm.